Question

1. CO₂ is a byproduct of cellular respiration. When does it form?

   	a.	intermediate step
   	b.	citric acid cycle
   	c.	glycolysis
   	d.	a & b
   	e.	all of these

Which of these are involved during the direct synthesis of a protein?

	a.	mRNA, small ribosomal subunit, amino acid
	b.	tRNA, large ribosomal subunit
	c.	RNA polymerase, transcription factors
	d.	a and b
	e.	all of these

1. The deletion of a single base pair in the DNA can result in

   	a.	a nonfunctional protein
   	b.	a shift in reading frame
   	c.	the wrong amino acids being  used in translation
   	d.	a & b
   	e.	all of these

1. During ____ , the DNA double-helix is opened and a small region is used to make mRNA.

   		DNA replication
   		RNA replication
   		transcription
   		translation
   		mRNA synthesis

Answer 1

Question 1

Answer: Cellular respiration consumes oxygen to oxidizes food and produces carbon dioxide and energy. It involves three steps: Glycolysis, pyruvate oxidation (intermediate step) and Krebs' cycle and electron transport chain. Glycolysis does not have decarboxylation step and no CO2 is released. Hence, option c and e are incorrect answers. Pyruvate oxidation (intermediate step) and Krebs' cycle involves decarboxylation steps and forms CO2. In intermediate step, pyruvate is oxidized to acetyl-CoA and CO2 by pyruvate dehydrogenase. In Krebs cycle, α-Ketoglutarate undergoes oxidative decarboxylation and forms succinyl-CoA and CO2. Hence, options d is the correct answer.

Question 2

Answer: mRNA, both subunits of ribosomes, tRNA and aminoacid are directly involved in the protein synthesis. mRNA contain codons for amino acids. tRNA carries amino acids and its anti codons binds to mRNA codons. Protein synthesis occurs on ribosomes. Hence, option d is the correct answer. RNA polymerase and transcription factors are involved in transcription but not in protein synthesis. Hence, options c and e are incorrect.

Question 3

Answer: Deletion of a single base pair in the DNA shifts the reading frame of the codons in the DNA. This results in the incorporation of wrong amino acid during protein synthesis and produce non-functional protein. Hence, option e (all of these) is the correct answer.

Question 4

Answer: The synthesis of mRNA from DNA is called as transcription. Hence, option 3 is the correct answer. DNA replication involves duplication of DNA. RNA replication involves duplication of RNA. Translation involves synthesis of proteins using mRNA codons. Hence, options 1, 2, 4 and 5 are incorrect.